The basics

UVB rays are the primary cause of sunburn and skin cancer. UVA rays penetrate deeply into the skin and cause wrinkles and also increase skin cancer risk. You need to use your sunscreen every day, all year round, even when it's cloudy, to protect your skin.

Sunscreen can help reduce your risk of skin cancer, but it may also prevent you from getting the vitamin D you need, so make sure you're getting enough.

SPF

If you're not wearing sunscreen, and your skin gets sunburned after 10 minutes in the sun, then it would take 15 times as long (150 minutes) to get sunburned when you're wearing SPF 15.

Although sunscreens with lower SPF are available, we recommend that everyone use a sunscreen with an SPF of 50 or higher, and it should contain either zinc oxide or titanium oxide. Sunscreen should be applied every 1½ to 2 hours.

Choosing a sunscreen

Water- or sweat-resistant?Ideally, sunscreens should be water-resistant, so they don't wear off when you're sweating or swimming. Even water-resistant sunscreens may stop working after 80 minutes in the water, or may rub off if you towel-dry yourself, so reapply at least every 2 hours or after swimming or sweating heavily.

Cream, gel, or spray on?Buy a brand and a type of sunscreen that you like. The way it's packaged isn't important as long as you use it. Some athletes prefer to use gel or spray-on sunscreen on their faces because cream sunscreen can irritate their eyes when they sweat.

Sunscreen for kidsChildren's sunscreens use ingredients that are less likely to irritate babies' and children's sensitive skin. The mildest sunscreens use only zinc oxide and titanium dioxide as active ingredients.

The American Academy of Pediatrics recommends keeping babies under 6 months out of the sun. For children 6 months old and older, use a sunscreen for children with an SPF of 15 or higher.

Sunscreen for tender skinIf you have sensitive skin or allergies, you may want to try sunscreens that use only zinc oxide and titanium dioxide as active ingredients and are labeled "chemical free." Avoid sunscreens with alcohol, preservatives, and fragrances.

If you can't tolerate any sunscreen, clothes are the best protection. Microfiber nylons and polyester give good protection, but most fabrics that can't be seen through will give reasonable protection, too. You can find clothing that has been tested and given an ultraviolet protection factor (UPF) rating.

How to apply sunscreen

Though choosing the right sunscreen is important, it's even more important that you apply it properly.

Apply early and often. Sunscreen should be applied 30 minutes before going outside and reapplied at least every 2 hours.

Be generous. Most people don't use enough sunscreen. You need about 2 tablespoons to cover your face and exposed areas of your body. If you’re using a spray, apply until an even sheen appears on the skin. Don't forget your nose, neck, hands, toes, and lips — many skin cancers develop on these areas. If you're bald, wear a hat or apply sunscreen to the top of your head. Protect your lips with a lip balm with SPF 15 or higher. When driving, be sure your hands and forearms are protected.